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“In 1983, he collected specimens of two new species-Nebria wallowae
and Nebria labontei-near Glacier Lake in Oregon’s Wallowa Mountains.
Both were collected between 6,500 and 6,700 feet. When he returned in
August of 2008, he had to hike to an altitude of nearly 8,150 feet
before he found them.”
” … there’s no question that the beetles are moving higher up the
mountains. And where I used to find hundreds of them, I’m often now
finding just a handful-or none at all.”
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Public release date: 1-Dec-2008
California Academy of Sciences
Contact: Stephanie Stone
sstone@calacademy.org 415-379-5121
Ice beetles impacted by climate change
California Academy of Sciences entomologist finds beetles moving to
higher ground
In the summer of 1968, Dave Kavanaugh set off on a hike that would
change the course of his life. As a second-year medical student at
the University of Colorado, he had joined a climbing club with a few
members of the biophysics department, and the group had set their
sights on Gray’s Peak-the ninth highest mountain in Colorado.
Kavanaugh, who has never been able to do anything slowly, scampered
up to the top of the peak in record time and sat down to wait for the
rest of the group. As he peeled an orange and gazed out at the
surrounding terrain, a sudden movement caught his eye. A small black
beetle had crawled up onto his boot. While most climbers would have
ignored (or possibly squashed) the small intruder, Kavanaugh whipped
a collecting vial out of his pack-beetle collecting had been a hobby
ever since he took an elective entomology course in college-and
scooped up the rare specimen. He had never seen it before in
Colorado, and as he learned when he got back to campus, neither had
many others. There were only two previous records of the species in
the state. “That was it,” says Kavanaugh with a grin. “I was hooked.”
The next year, he left the medical field to pursue a career in
entomology. After earning a Master’s degree from the University of
Colorado, he enrolled in a Ph.D. program at the University of
Alberta. Selecting a specialty was easy-he chose to focus on beetles
in the genus Nebria because, as Kavanaugh says, “they live where I
like to be-up in the mountains.” Over the next few years, Kavanaugh
scoured mountainsides from Washington to Wyoming and beyond in search
of Nebria beetles. During the summer of 1971, he lived in a
professor’s camper, logging over 25,000 miles and collecting beetles
from more than 400 different sites. By the late 1970s, he had
exhausted all of the vehicle-accessible options and began backpacking
into more remote regions, including Oregon’s Wallowa Mountains and
the Queen Charlotte Islands. When he arrived at the Academy in 1978,
Kavanaugh was already the world’s foremost expert on North American
Nebria beetles.
Mostly mountain dwellers, Nebria beetles are perfectly adapted for a
life in frigid climates. Enzymes in their bodies have evolved to
function at very low temperatures, allowing them to stay active when
other animals would shut down. The beetles also produce a chemical
that works like antifreeze to lower the freezing point of water,
preventing their bodies from freezing solid even in subzero winter
weather. During the day, these cold-adapted creatures stay safe from
predators-and the heat of the sun-by hiding under rocks. At night,
they emerge from their hideouts and crawl onto nearby snowfields and
glaciers to feed on other insects that have been stranded on the
snow. Many scientists might have preferred a study subject adapted to
slightly warmer climates, but Kavanaugh seems to be just as
comfortable in the cold as his beetles. “Fifteen below is actually
pretty nice,” he laughs. “It’s 50 below that you want to avoid.”
After many months in the mountains over the course of his career,
Kavanaugh has documented 85 North American species of Nebria beetles,
43 of which were new species that he named and described.
When Kavanaugh first started collecting beetles, DNA sequencing work
was barely in its infancy-the practice did not begin to pick up steam
until after the Human Genome Project was launched in the late 1980s.
Once DNA sequencing became an affordable tool for evolutionary
biologists and taxonomists, it changed the science of specimen
collection and storage. Most entomology specimens had historically
been pinned and stored in drawers, making it easy to measure and
compare specimens. However, in order for insect specimens to yield
valuable DNA data, they must be stored in alcohol or another
preservative. To get the most possible information about a particular
species, entomologists now need to prepare specimens both ways.
By the time the Academy moved into its new home in Golden Gate Park
in 2008, Kavanaugh had the largest and most comprehensive collection
of dry, pinned Nebria beetles anywhere in North America, but he was
missing DNA samples for a number of the species he collected early in
his career. And so it was that more than 30 years after his first
major cross-country quest for Nebria beetles, Kavanaugh set off on
another epic adventure, retracing his steps in search of DNA samples
for each of the species in his collection. Between June 22 and August
20 of 2008, he revisited 67 collecting sites in the mountains of
eight different states. He had dutifully written down the exact
location of every specimen he ever collected, so he knew exactly
where to look. The problem was that the beetles were no longer there.
“I have a whole new perspective on change now,” says Kavanaugh as he
sits in his office a few months later. “I was completely unprepared
for the amount these habitats had changed in the past few decades. In
some places, I found that the picturesque mountain stream I
remembered was now a ski resort. Perhaps more startling, I realized
that in many areas the tree-line was moving up the mountain and the
glaciers were retreating.” Because of their snowfield hunting
practices, most Nebria beetles live above the tree-line, favoring
barren rocky patches where they can run without wading through tall
grasses or shrubs. However, the altitudes that once provided them
with ideal rocky habitats now often host lush forests or meadows-and
the open snowfields that were once extensive are now often gone.
Kavanaugh’s first stop on his DNA mission was Sonora Pass in the
Sierra Nevada range. In 1981, he had described a new species from the
site, which he named Nebria sonorae. The next year, he collected
dozens of these beetles from a stream bed at an altitude of 9,025
feet. However, when he returned to the exact spot in June of 2008, he
couldn’t find a single specimen. With the light fading, he didn’t
have time to hike up higher, but he vowed to return and continue his
quest. Two months later, Kavanaugh made a second trip to Sonora Pass,
starting his search at 9,025 feet and working his way up the
mountain. “I turned over every single rock along the stream on the
way up,” says Kavanaugh. “I found a lot of other things, but no
Nebria sonorae.” After hiking all day, Kavanaugh had finally decided
it was time to turn around when he got to the base of a small
waterfall. There, at an altitude of 9,250 feet, he found 11 Nebria
sonorae beetles that had washed down the stream and accumulated at
the base of the falls. “These guys were more than 200 feet higher
than they were back in 1982, and their actual habitat was probably
much further up the mountain,” says Kavanaugh.
As he traveled to collecting sites in Oregon and Colorado, Kavanaugh
realized that his Sonora Pass experience was not an isolated
incident-it was part of a trend. In 1983, he collected specimens of
two new species-Nebria wallowae and Nebria labontei-near Glacier Lake
in Oregon’s Wallowa Mountains. Both were collected between 6,500 and
6,700 feet. When he returned in August of 2008, he had to hike to an
altitude of nearly 8,150 feet before he found them. On Quandary Peak,
in Colorado’s Rocky Mountains, he collected Nebria suturalis beetles
at altitudes as low as 11,700 feet in 1968. In August of 2008, he
hiked as high as 12,400 feet but could not find a single specimen. He
had to go to neighboring Mt. Evans, to heights of 13,100 feet and
above, before he finally found Nebria suturalis again.
Closer to home, Kavanaugh found more startling data in the Trinity
Alps, a few hours north of San Francisco. In August of 1980, while
leading a Boy Scouts trip for his son’s troop, he had collected a new
species, later named Nebria turmaduodecima, on a large snowfield near
Upper Caribou Lake at elevations between 6,900 and 7,500 feet. This
August, the snowfield at Upper Caribou Lake was nonexistent.
Kavanaugh asked one of his graduate students, Sean Schoville, to
visit nearby Thompson Peak to see if the species might still exist at
higher altitudes. Schoville was indeed able to find Nebria
turmaduodecima at an elevation of just over 7,900 feet. However, the
glacier on the north face of Thompson peak, which was once one of the
largest glaciers in California, is now calving. If the glacier breaks
up and recedes, the winter snow accumulation will melt more quickly
in future years, perhaps eliminating the last remaining habitat for
Nebria turmaduodecima.
During the last Ice Age, Nebria beetles were much more widespread. As
the climate gradually warmed, they moved higher up into the mountains
and populations became increasingly isolated from one another.
Although their range is now much smaller than it once was, these
tough predators have survived a great deal of change. However, they
may now be running out of room to move. “Some of the things I saw
this summer shocked me,” says Kavanaugh. “Perhaps it can’t all be
blamed on climate change. It’s possible that some of the forestation
I witnessed was part of a natural forest cycle. But there’s no
question that the beetles are moving higher up the mountains. And
where I used to find hundreds of them, I’m often now finding just a
handful-or none at all.”
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